This is my 2nd MDX, the first was an 03. Anyway, bought this used with 89K miles. Drives great but obviously the more I drive it I start to notice things. I'm hearing a metal scraping noise in the rear of the vehicle. Mostly at low speeds or maybe when turning. Driving straight at high speeds I hear nothing. Maybe the engine noise dampens it at higher speeds. Took both rear wheels off and inspected brakes, took whole caliper off and everything. They look good. Rotors are smooth, pads actually look very new. Any ideas or suggestions? I'm not sure when the rear differential was changed last. Could that be causing it? Thanks in advance!